Routing or bridging? need help

[KamikazeMicrowave]

Heres my situation. Sorry if this is painfully obvious since networking isnt my strong point and im still in schooling...

At work some time ago our IT person was not an actual IT guy, but rather someone who knew a little about computers. When he set up the network he used the 199.0.9.X subnet. As you know thats a wide area address. Therefore I'm in the process of changing our computers over to a better subnet, like 192.168.9.X.

From my understanding I could set up a network bridge that would connect the 199.0.9 network with the new 192.168.9 network correct? Well long story short I tried and ultimately took the network down.

So either I did it wrong or a bridge wont work in my case and I should route instead. Heres what I did to set up the bridge

[Clansman]

Hi,

You need a router and/or some kind of NAT.

Conceptually, a bridge is used to join 2 physical ethernet segments on the same layer 3 segment. i.e.: 2 hubs+1 bridge -> 1 network (192.168.0.0/255.255.255.0). A bridge is a layer 2 router - not layer 3.

You need one of the following:

- a router to allow communications between the 199.0.9.X and 192.168.9.X - This approach implies coexistence of both networks in a way one network sees the other as a different network.
example: 192.168.168.32 wants to communicate with 199.0.9.5:
192.168.9.32 -> router -> 199.0.9.5

- a NAT router to transparently (and staticly) translate 199.0.9.X addresses into 192.168.9.X - This approach also implies the coexistence of both networks, but none of the networks has any direct way of knowing that there *is* another network. Hosts with 199.0.9.X ips are accessed by 192.168.0 network with equivalent 192.168.9.X addresses.
example: 192.168.9.32 wants to communicate with 199.0.9.5 - not possible anymore. host is now 192.168.9.5:
192.168.9.32 -> 192.168.9.5 -> NAT router/translation -> 199.0.9.5

One of these two different solutions may fit your needs.

Cheers,
_________________
http://www.pjvenda.org

[KamikazeMicrowave]

Ok well heres two other question then. Do these seperate network segments have to be on seperate switches to be able to route between one another? I'm thinking no but I want to be sure. And secondly, do you thinking a pentium 3 500mhz machine with 256megs of ram will suffice as a router on a network with roughly 80-100 clients? The traffic that will go over the router is fairly low bandwith. Its actually just telnet sessions. My boss has just kind of put me in charge of the move while he does other things.

I wrote a script that can change all of my windows clients to a new 192.168.9 address but certain things will take awhile to change over. For example we have a unix server thats acessed by many remote clients. That will either have to stay at its current address of 199.0.9.77 or have a second ip address bound to it, in which case I still have to have things routed to it.

[Clansman]

[thepustule]

[1clue]

Hang on a minute.

You mention 80-100 clients. Are these all static addresses or are you using DHCP? Do you use DNS? The reason I'm asking is that it MIGHT be a lot easier to set up a DHCP/DNS servers and just change the network over in one big step. If most of your boxes are just DHCP clients, then you'd need to change a few servers and then change the DHCP configuration, and then reboot all the machines.

The key here is to design your new network appropriately and plan everything out. The WINS server will keep track of everyone's name, and you can (and should) set up WINS through DHCP anyway. Same with DNS and such. We did this not too long ago. We also broke the network up into VLANs to avoid virus overload from The Dark Side, and for other security concerns. Not sure if that's necessary, but it depends on how fast your company is growing.

It just seems that if your goal is to switch everyone over to a private network scheme, then making a bridge might be just putting a patch over an existing problem.

[thepustule]

[KamikazeMicrowave]

[1clue]

What a drag.

Your situation is screaming for something like DHCP. Our changeover would still be in its infancy without it.

I wonder: Is it just the static addresses you need, or does it have to be a static configuration? You can assign addresses using DHCP by MAC address if you want. Just ping your DHCP server with the original address, copy the name, IP and MAC address from your ARP table and fill it in on the DHCP server. It's painful, but it gives you centralized control and you don't have to type in all those MAC addresses, or run around to each machine in order to fix anything.

[Clansman]